This invention relates to automatic titrations and titration apparatus, and in a preferred embodiment the invention is concerned with coulometric titration of water using the Karl Fischer reaction with apparatus of the type described in U.S. Pat. No. 3,726,778 to Levy and Seltzer. As described in that patent, such titrations are subject to positive and negative baseline drift, that is, drift away from the endpoint condition not resulting from sample addition. Such drift can be caused by a variety of factors, including side reactions in the titration mixture which either generate or consume the substance being titrated. In coulometric titration of water, aldehyde or ketones in samples will react to produce water. While U.S. Pat. No. 3,726,778 provides one approach to compensation for drift, it would be desirable to provide an apparatus and method adapted for determining accurately the actual amount of drift in each titration and automatically correcting the titration results.